How Predictable Is Popularity?

Ozgun Atasoy describes a research experiment that explored the question:

As one would expect, when people are better connected, they tend to unite around popular decisions. But research also suggests that social connection — fostered by Twitter, say — also makes crowds fundamentally less predictable. With social media connecting people to an unprecedented degree, it is possible that the sudden emergence of unexpected collective action will be a defining feature of this era.

Matthew Salganik, Peter Dodds, and Duncan Watts conducted large-scale experiments to investigate the effect of the strength of social influence on collective action. People were given a list of previously unknown songs from unknown bands. They listened to the songs and downloaded them if they wanted to. In the independent condition, people did not see other people’s choices. In the social influence condition, people saw how many times each song had been downloaded by others. The collective outcome in the social influence condition was more unequal. That is, popular choices were much more popular under social influence. When the researchers increased the strength of social influence by displaying the songs in a table ordered by popularity, the collective outcome became even more unequal.

After the events around Gezi Park unfolded, there were attempts at explaining why they happened. Events seem inevitable retrospectively. But the truth is most people did not know that the uprising was coming. But was it knowable? In other words, could a sophisticated observer accurately predict the events?

Salganik, Dodds, and Watts looked at the collective outcomes in eight different “worlds.” That is, eight separate groups of people downloaded songs under social influence. The collective outcomes in different “worlds” were different. Even though people in different “worlds” were indistinguishable and they did the same task under the same conditions, the collective outcomes were different. When the researchers increased the strength of social influence, the collective outcome became even more unpredictable. That is, the difference between the popularities of a given song in different “worlds” increased as the strength of social influence increased. Apparently, in collective decisions there is an inherent unpredictability that cannot be resolved by carefully examining the initial conditions and decision makers. Stronger social influence results in more unpredictability.